Pentaamine(dinitrogen)ruthenium(II) chloride is an inorganic compound with the formula [Ru(NH3)5(N2)]Cl2. It is a nearly white solid, but its solutions are yellow. The cationic complex is of historic significance as the first compound with N2 bound to a metal center. [Ru(NH3)5(N2)]2+ adopts an octahedral structure with C4v symmetry.
Preparation and properties Pentaamine(dinitrogen)ruthenium(II) chloride is synthesized in an aqueous solution from pentaamminechlororuthenium(III) chloride, sodium azide, and methanesulfonic acid:Allen, A. D., Bottomley, F., Harris, R. O., Reinsalu, V. P., Senoff, C. V. "Pentaammine(Nitrogen)Ruthenium(II) Salts and Other Ammines of Ruthenium" Inorganic Syntheses, 2007, volume 12, pp. 2-8. [Ru(NH3)5Cl]Cl2 + NaN3 → [Ru(NH3)5N2]Cl2 + ... If it is to be used in situ, the cation can be made more conveniently from ruthenium(III) chloride and hydrazine hydrate: RuCl3 + 4 N2H4 → [Ru(NH3)5N2]2+ + ...
This N2 complex is stable in aqueous solution and has a relatively low ligand exchange rate with water. Being a d6 complex, the Ru-N bond is stabilized by the pi backbonding, the donation of metal d-electrons into the N2 π* orbitals.Taube, H. "Chemistry of Ruthenium(II) and Osmium(II) Ammines" Pure and Applied Chemistry, 1979, volume 51, p. 901–12. The related metal ammine complex [Os(NH3)5(N2)]2+ is also known.
Reactions The dinitrogen ligand is not reduced by aqueous sodium borohydride.J. Chatt, R. L. Richards, J. F. Fergusson and J. L. Love, "The reduction of nitrogen complexes" Chem. Commun. 1968, 1522. Nearly all known reactions of this compound are displacement reactions. Pentaamine(halogen)ruthenium(II) halides can be synthesized by treating [Ru(NH3)5N2]2+ with halide sources: [Ru(NH3)5N2]2+ + X− → [Ru(NH3)5X]+ + N2
[Ru(NH3)5N2]2+ forms the symmetrically bridging symmetrical dinitrogen complex [(NH3)5Ru-NN-Ru(NH3)5]4+.
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